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Although this is a point source, due to the distributional nature, long-range transport, and multiple sources of the pollution, it can be considered as nonpoint source in the depositional area. Atmospheric inputs that affect runoff quality may come from dry deposition between storm events and wet deposition during storm events.
Usually, permitted point sources of water pollution, such as wastewater treatment plants, have high discharge treatment costs, whereas nonpoint sources of water pollution, such as agriculture, have low costs of pollution reduction. Therefore, it is generally assumed that most trades would take place between point sources and nonpoint sources. [54]
A point source of pollution is a single identifiable source of air, water, thermal, noise or light pollution. A point source has negligible extent, distinguishing it from other pollution source geometrics (such as nonpoint source or area source). The sources are called point sources because in mathematical modeling, they can be approximated as ...
This water pollution has a number of detrimental effects on human health and the environment. Unlike point source pollution, nonpoint source pollution arises from numerous and diverse sources, making identification, monitoring, and regulation more complex.
In many watersheds, nonpoint sources are the principal cause of noncompliance with water quality standards. [105] EPA and states may employ a CWA regulatory mechanism called total maximum daily load (TMDL) to establish stringent pollution controls and may apply the requirements to both point sources and nonpoint sources.
Sources of water pollution are either point sources or non-point sources. [4] Point sources have one identifiable cause, such as a storm drain, a wastewater treatment plant, or an oil spill. Non-point sources are more diffuse. An example is agricultural runoff. [5] Pollution is the result of the cumulative effect over time. Pollution may take ...
Nonpoint source pollutants, such as sediments, nutrients, pesticides, fertilizers and animal wastes, account for more than half of the pollution in U.S. waters. [26] Congress exempted some water pollution sources from the point source definition in the 1972 CWA and was unclear on the status of some other sources.
TMDL is the end product of all point and non-point source pollutants of a single contaminant. Pollutants that originate from a point source are given allowable levels of contaminants to be discharged; this is the waste load allocation (WLA). Nonpoint source pollutants are also calculated into the TMDL equation with load allocation (LA). [7]